Process for producing varicolored fabrics via the selective dyeing of cellulosic fabrics with different dye types

ABSTRACT

A process has been developed for the selective dyeing of cellulosic fabrics with different types of dyes. This process consists of the application of a coating mixture to a fabric either entirely on one side, in a selected area, as a stripe, or in another design. The design may also be painted or printed on the fabric. The coating solution contains either a polymer or polymer and crosslinking agent. The fabric is then dyed with a disperse dye and a cotton dye. The polymer treated part of the fabric is dyed with the disperse dye while the remainder of the fabric is dyed with the cotton dye. By this technique, fabrics were produced which were one color on one side and another color on the other, or which have stripes or designs on the fabric.

United States Patent Harper, Jr. et a1.

PROCESS FOR PRODUCING VARICOLORED FABRICS VIA THE SELECTIVE DYEING OF CELLULOSIC FABRICS WITH DIFFERENT DYE TYPES Inventors: Robert J. Harper, Jr., Metairie;

Eugene J. Blanchard, New Orleans; John T. Lofton; Gloria A. Gautreaux, both of Metairie, all of La.

The United States of America as represented by the Secretary of Agriculture, Washington, DC.

Filed: Nov. 5, 1971 Appl. No.: 196,214

Assignee:

References Cited UNlTED STATES PATENTS 4/1970 Sokol 8/18 1 Nov. 27, 1973 1,610,786 12/1926 Jacoby 8/65 3,432,251 3/1969 Fisher ..8/69

Primary Examiner-Donald Levy Attorney-R. Hoffman et a1.

[57] ABSTRACT A process has been developed for the selective dyeing of ce'llulosic fabrics with different types of dyes. This process consists of the application of a coating mixture to a fabric either entirely on one side, in a selected area, as a stripe, or in another design. The design may also be painted or printed on the fabric. The coating solution contains either a polymer or polymer and crosslinking agent. The fabric is then dyed with a disperse dye and a cotton dye. The polymer treated part of the fabric is dyed with the disperse dye while the remainder of the fabric is dyed with the cotton dye. By this technique, fabrics were produced which were one color on one side and another color on the other, or which have stripes or designs on the fabric.

2 Claims, No Drawings PROCESS FOR PRODUCING VARICOLORED FABRICS VIA THE SELECTIVE DYEING OF CELLULOSIC FABRICS WITH DIFFERENT DYE TYPES A non-exclusive, irrevocable, royalty-free license in the invention herein described, throughout the world for all purposes of the US. Government, with the power to grant sublicenses for such purposes, is hereby granted to the Government of the United States of America.

This invention relates to the dyeing of cotton and other cellulosic containing fabrics with disperse dyestuffs. More particularly, this invention relates to a process which permits cotton and other cellulosic fabrics to be dyed in a selective manner before or after crosslinking.

Finally, this relates to a process by which cotton fabrics can be dyed selectively in certain areas. This is achieved by treating large areas on one side of fabric with a polymer that can be dyed with a disperse dye. The rest of the fabric is then dyed with a regular cotton dye. By this method, a two colored cotton fabric is produced with one part of the fabric dyed one shade or color while the other part of the fabric is dyed a different shade or color.

Heretofore, it is well known that disperse dyestuffs have little affinity for cellulosic fabrics. Likewise, it is well known that only limited systems exist for the dyeing of crosslinked fabrics. Of more importance to this work is that apart from printing techniques, there are few methods available for the piece-dyeing of cotton or blended goods with disperse dyestuffs so that a pattern, stripe or other design can be produced on the fabric.

This process is designed to achieve the selective dyeing of specific portions of fabrics with disperse dyestuff whether or not the fabric is crosslinked. This is achieved in the following manner. First, cotton or other cellulosic containing fabrics are treated with polymer emulsions which are thickened in a manner to be described later. These polymer emulsions have been applied to fabric in a number of ways. In one case, the polymer was applied only to one side of the fabric. In another, the polymer was applied to one side of a fabric but only in the form of stripes (with certain segments blocked out). In another, the polymer was painted or printed on the fabric in the form of various designs such a as circles, dots, or even pictures of objects. Ultimately, object designs can be employed as in screen printing or roller printing techniques. Once the polymer is dried and cured, these fabrics were dyed in a bath containing disperse dye. The sections of the fabric which had been treated with polymer were dyed with the disperse dyestuff while the other sections were relatively undyed. By this method fabrics were obtained that were dyed on one side, in stripes or in other designs according to where the polymer had been placed on the fabrics. This procedure can be employed both on undyed and dyed cotton fabrics. Likewise, it has been found to work on crosslinked or noncrosslinked cotton fabrics.

Of course this process can be combined with a dye procedure using a normal cotton dye to produce bicolored fabrics. In this method, the fabric is dyed with a disperse dye and then it is dyed with a normal cotton dye, such as a reactive dye, direct dye or vat dye. In this method, the part of the fabric treated with the polymer is dyed the color of the disperse dye while the untreated part of the fabric is dyed the color of cotton dye. The

reverse procedure in which the fabric is dyed first with the cotton dye and then with the disperse dye also is effective. Techniques using both dyes in the dye bath are likewise effective.

Variations using crosslinking agent can also be used. In one case, polymer and crosslinking agent are included in the coating formulation. The fabric is then cured. When the fabric is dyed, there is a sharper delineation between the area dyed with the cotton dye (the noncrosslinked area and the area dyed with the disperse dye (the polymer treated area). The other variation using crosslinking agent is as follows. The fabric is dyed with a cotton dye. It is crosslinked and then coated with the polymer; then it is dyed with the disperse dye. The crosslinking treatment can also be performed either after the polymer coating or after the disperse dyeing. The result in any case is a bicolored crosslinked cotton fabric produced via piece dyeing techniques.

At this point, the method of applying the polymers to the fabrics will be considered. The coating solution is prepared so that it will have the desired concentration of polymer or polymer and crosslinking agent plus sufficient thickening agent so that the mixture will not penetrate the fabric. Examples of thickening agents employed are hydroxyethyl cellulose, carboxymethyl cellulose and polyacrylic acid. The polyacrylic acid is modified with ammonia to control the viscosity and fluidity of the coating medium. Once the coating mixture is dried and cured on the fabric,the fabric is now ready for dyeing. (An intervening wash step is optional.) The ability to dye these polymer treated fabrics is valuable for several reasons. This provides a method for the selective dyeing of designated regions of cotton fabrics. Thus, it provides a method for obtaining certain types of novelty and fashion fabrics which are usually difficult or expensive to obtain. The fact that the method is applicable to either crosslinked or noncrosslinked fabrics lends an element in finishing that is not normally available. Thus dye shade selection can be deferred to the last moment and this is helpful in reducing overall factory inventory. Next, with precured fabrics, a broader range of dyestuffs can be used because the goods are not exposed to either crosslinking agents, catalysts or the very high temperatures usually employed in finishing.

While this technique has been employed on cotton fabrics, it should be amenable to cellulose-polyester blended fabrics, if relatively mild dyeing conditions or no dye carrier is employed in the dyeing operation.

While a number of polymers and copolymers have been used in finishing prior to dyeing, only those with relatively low functionality such as polyethylene perform poorly. Polyacrylate copolymers are moderately effective. Polyurethanes are likewise effective and particularly effective are butadiene-acrylonitrile copolymers and polyacrylonitriles, In this respect it can be readily seen that nitrile, urethane or amide linkages are preferred groups in polymers to promote disperse dyestuff absorption. From a practical point of view, polymers with glass transition temperature below room temperature would appear to be most suitable. Dye uptake can be achieved with polymers of high glass transition temperatures but the high add-ons required in this process lead to fairly stiff fabrics.

Numerous polymers are available to promote dye uptake. It is only necessary to select those which possess the desired functionality or chemical groups that when used in fibers have shown good affinity for disperse dyes. Some groups which are particularly effective are copolymers in which an acrylonitrile moiety (A) is present and those in which a urethane (B) or amide (C) type linkage is formed. Acrylate [sail] [ii] copolymers likewise have shown good performance as well as butadiene-styrene copolymers.

Once the requirement for the dye acceptability of the polymer becomes recognized, the process variables can be easily worked out by one knowledgeable in the textile field. Some variations of this process are as follows. In the initial step, crosslinking agent is applied to fabric and the fabric is raised to durable-press or wash-wear performance standards. The polymer can be applied before or after the crosslinking resin. Likewise the polymer treatment can be employed without any crosslinking agent.

Once the treatment with the polymer and the optical treatment with the crosslinking agent is completed, the next step consists of the application of the disperse dyestuff to the fabric. The method most commonly employed in this work was placing the disperse dyestufiin a bath and heating the fabric at an elevated temperature in the dyebath containing the disperse dyestuff. Because crosslinking finishes are sensitive to bath pH at higher temperatures, an important consideration is to use dyestuffs and baths which can be adjusted close to pH 7 if necessary.

In addition to dyebath techniques, other methods usually employed with disperse dyestuffs can also be employed. One such method is the thermosol method, which is a high temperature fixation method frequently used with synthetic fabrics. While the nature of the polymers employed in this work are such that dyebath techniques would seem to be preferred, use of the thermosol type application using dyestuffs with low sublimation tendencies should be possible.

in order to obtain the bicolored fabrics, a cotton dye is used in combination with the disperse dye. That is, the polymer treated portion of the fabric is dyed one color with the disperse dye while the remainder is dyed with a cotton dye, such as a reactive, direct or vat dye. Either dye type (disperse or cotton dye) can be used first and sytems using both dyes in the same bath should be applicable. By this method, multicolored fabrics such as front and back, with stripes and other designs on them can be produced.

Of course, the process can be applied to previously dyed fabrics thus providing another way of achieving fabrics dyed with more than one color.

Provided the dyeing technique is sufficiently mild, the application of this process to blended fabrics may be particularly beneficial. It is well known that such blended fabrics required dyeing by two classes of dyes, one for the dyeing of the polyester component, the other for dyeing of the cotton component. This entails considerable processing and comparatively high dye costs. By contrast, polymer treated blended fabrics can be dyed on one side or in stripes with a single dye system with the accompanying reduction in processing costs.

Concentration of Agents The amount of polymer used in the coating formulations should be from 10-30 percent with 20 percent being about the right concentration. Total fabric addon of polymer ranges from 3-12 percent with about 6-l0 percent being the ideal total add-on. Some variation in concentration and wet pickup can be made to control polymer add-on to the desired 6-10 percent level.

In cases in which crosslinking agent is used in the coating formulation, a level of from 8-l4 percent can be used. One such typical crosslinking agent used in this study was dimethylol dihydroxyethyleneurea.

Although examples of these techniques will be given only for one side dyeing, striping and the application of designs to fabric, numerous variations should be possible for anyone skilled in the art of finishing, dyeing or printing.

Example 1 An 8.5 02. cotton twill fabric was face coated with a formulation composed of 20 parts of polyurethane, 1.35 parts of carboxylated acrylic polymer, 1.5 parts of ammonium hydroxide, and 77.15 parts of water. The coating mixture was spread over the face of the fabric by means of a laboratory coating device. After coating, the fabric was placed in a forced draft oven and dried for 15 min. at 60 C. Similar experiments were performed in which the polyurethane was replaced in the coating formulation with either a polyacrylate or a butadiene-acrylonitrile copolymer.

Samples of these fabrics plus untreated cotton fabric controls were dyed with Disperse Yellow 88 in the following manner. The dye bath was prepared by dissolving 1 part of the disperse dye in 99 parts of water and heating to C. The fabrics were dyed for 30 min. and then rinsed with distilled water followed by laundering. The face sides of the fabrics containing the polymers were dyed a very deep yellow while the back side of the fabric had only a light yellow appearance. In addition, untreated cotton control had only a light yellow appearance. These results demonstrate that selective dyeing of piece goods with a disperse dye is possible by selective placement of polymer because of the affinity of the disperse dyestuff for the polymer coated area.

Analogous results were obtained when samples of the various fabrics were dyed in a similar fashion with Disperse Red 86 except in this case the side of the fabric given the polymer treatment was dyed red.

Example 2 Samples of the various coated but undyed fabrics produced in Example 1 were padded with a solution containing 9 percent dimethylol dihydroxyethyleneurea and 0.6 percent zinc nitrate hexahydrate. The fabrics were dried for 7 min. at 60 C and cured for 15 min. at C. Samples of these fabrics were dyed with Disperse Yellow 88 and Disperse Red 86 as in Example 1. In each case, the disperse dye was retained on those parts of the fabric which had been coated with polymer and not on the parts that had not been coated with polymer. The fact that the fabric had been crosslinked did not seem to reduce the ability of the disperse dye to dye the polymer coated surface.

Example 3 An 8.5 oz. cotton twill fabric was partially face coated so that a striped pattern was formed on the fabric surface. The stripes were formed by placing l-inch wide strips of masking tape over the length of the fabric at l-inch intervals. The fabric surface was then face coated with a formulation composed of 20 parts of polyurethane, 1.35 parts of carboxylated acrylic polymer, 1.5 parts of ammonium hydroxide, and 77.15 parts of water. The coating mixture was spread over the face of the fabric by means of a laboratory coating device. Polymer was deposited on the fabric only in the areas between the strips of masking tape. The fabrics were dried in a forced-draft oven for min. at 60 C. After drying, the strips of masking tape were removed from the fabric surface.

With other fabrics, the identical procedure was employed except that the polymer was a polyacrylate in one case and a butadiene-acrylonitrile copolymer in the other. Then these fabrics were dyed with 1 percent Disperse Yellow 88 as in Example 1. The polymer coated bands on the fabrics were dyed a deep yellow while the bands containing no polymer had only a pale yellow appearance. This occurred because the disperse dye was absorbed only by the bands containing polymer thereby giving the fabrics a striped effect. These results demonstrate that it is possible to produce striped fabrics by the selective placement of polymer bands on the fabric prior to dyeing. A similar procedure using 1 percent Disperse Red 86 produced analogous results except that the polymer bands were dyed a deep red in this case.

Example 4 Other undyed samples from Example 3 were crosslinked using dimethylol dihydroxyethyleneurea as in example 2. Then these fabrics were dyed with 1 percent Disperse Yellow 88 and 1 percent Disperse Red 86 using the procedure outlined in Example 1. In each case, in the washed samples, the polymer stripes in the fabric were dyed a deep yellow or red, respectively, while the nonpolymer treated sections were relatively lightly dyed.

Example 5 In this case, fabric was face coated with a coating formulation containing polymer and crosslinking agent using the same process and procedure outlined in Example l. One coating formulation contained 20 percent polyurethane, 11.4 percent dimethylol dihydroxyethyleneurea, 0.7 percent zinc nitrate hexahydrate and 1.0 percent hydroxyethyl cellulose. A second formulation was prepared using 20 percent polyacrylate, l 1.4 percent dimethylol dihydroxyethyleneurea, 0.7 percent zinc nitrate hexahydrate and 0.8 percent hydroxyethyl cellulose. A third formulation was also prepared in which the polyacrylate was replaced with a butadiene-acrylonitrile copolymer. Each of the fabrics were dried and then cured for min. at 130 C.

Samples of these fabrics were then dyed with a bath containing 1 percent Disperse Blue 79 for a period of 1 hr. at 80-90 C. After these fabrics had been rinsed and reheated in an aqueous bath containing 0.1 percent wetting agent, samples of each fabric dyed with the disperse dye were dyed with a red, orange, or yellow reactive dye to give fabrics which were blue on one side and red, orange or yellow on the other side depending upon the color of the reactive dye employed. The reactive dyes employed were Reactive Red 1 (CI. 18158), Reactive Orange 4, and Reactive Yellow 22.

The dyeing with the reactive dye consisted of inserting the fabrics into a bath containing 2 percent reactive dye (based on weight of water) and 40 percent sodium sulfate (based on weight of fabric). The samples were stirred for 15 minutes, removed from the dye bath, 30 percent sodium carbonate (based on the weight of fabric) was added and then fabric samples were reinserted into the dye bath and stirred for 15 min. The fabrics were then rinsed in cold water and heated in a hot bath containing wetting agent.

The dried samples were dyed the color of the disperse dye on the side where they had been polymer treated and dyed on the other side the color of the reactive dye. This experiment again illustrates that this method can be used to produce a cotton fabric that is dyed one color 'on one side and a second color on the other side.

Example 6 The coating formulations containing polymer and crosslinking agent were applied to a fabric in a striped pattern using the procedure outlined in Example 3. After the fabrics had been coated, they were crosslinked and dyed with disperse and reactive dyes using the procedure followed in Example 5. In each case, the part of the fabric that had been striped with polymer and crosslinking agent was dyed the color of the disperse dye while the untreated fabric was dyed the color of the reactive dye. By using a blue disperse dye and orange, red or yellow reactive dyes, fabrics were produced with a striped front that was blue-orange, blueyellow or blue-red.

The reverse procedure in which the fabric was dyed with a reactive dye, then a disperse dye, gave analogous results. These experiments therefore provide a route to two-colored fabrics. This type of process yields specialty cotton fabrics which cannot be simply obtained by another route and readily demonstrate the viability of the process.

EXAMPLE 7 Coating formulations were prepared using polymer and thickener. The formulations were painted on cotton fabrics with a brush to produce various designs such as circles, squares, and other geometric shapes. Objects were also painted on these fabrics.

A typical formulation was prepared using 20 percent polyacrylonitrile copolymer, 5 percent of an acrysol thickener and a small amount of ammonium hydroxide. Other formulations were prepared using other nitrile containing polymers, polyacrylates, polyurethanes and butadiene-styrene copolymer latices. These coating solutions were applied to both crosslinked and noncrosslinked cotton fabrics. The fabric coating was then dried for 7 min. at 60 C and cured for 10 min. at C.

These fabrics were then dyed with a disperse red, Genacron Brilliant Red BRP, using 1.5 percent dye in a bath at 80-90 C for 1 hr. ln each case, the designs, circles, squares, and other geometric shapes were selectively produced on these fabrics. This occurred regardless of whether or not the fabric was crosslinked. By this method, it is indicated therefore that it is possible to produce printed fabrics using piece-dyeing techniques and further indicates that dye deposition on fabric can be controlled by a polymer pretreatment.

Example 8 In this case, coating formulations of the type used in Example 6 containing both polymer and crosslinking agent were painted on fabric as had been done in Example 7. These fabrics were then dyed with a disperse dye and a reactive dye using the dyes and dye processes reported in Example 6. By this method, the background which was untreated was dyed the color of the cotton or reactive dye while the designs were dyed the color of the disperse dye.

We claim:

1. A method of dyeing selected areas, less than the whole area of the fabric, on the surfaces of a cellulosic fabric one color using a first dye which is a disperse dye and the non-selected areas another color using a second dye which is a cotton reactive dye, which method comprises coating the areas of the cellulosic fabric selected for dyeing with said first dye with a polymer emulsion coating composition consisting of about percent of a member selected from the group consisting of a polyurethane, a polyacrylate and a butadieneacrylonitrile copolymer, about 1.35 weight percent of carboxylated acrylic polymer, about 1.5 weight percent of ammonium hydroxide, and the balance water, drying the cellulosic fabric that has been coated in selected areas for 10 minutes at a temperature of C. and thereafter dyeing the said fabric first with the said first dyestuff which is a disperse dyestuff and subsequently with the said second dyestuff which is a cotton reactive dyestuff to produce a fabric wherein the areas selectively coated are dyed with the disperse dyestuff and the non-coated areas are dyed with the cotton reactive dyestuff.

2. A method of dyeing selected areas, less then the whole area of the fabric, of the surfaces of a cellulosic fabric, which method comprises coating the areas of the cellulosic fabric selected for non-dyeing with a polymer emulsion coating composition consisting of about 20 weight percent of a member selected from the group consisting of a polyurethane, a polyacrylate and a butadiene-acrylonitrile copolymer, about 1.35 weight percent of carboxylated acrylic polymer, about 1.5 weight percent of ammonium hydroxide, and the balance water, drying the cellulosic fabric that has been coated in selected areas for 15 minutes at a temperature of 60 C. and thereafter dyeing the said fabric with a cotton reactive dye to produce a fabric wherein only the areas not selectively coated by the recited coating composition are dyed. 

2. A method of dyeing selected areas, less then the whole area of the fabric, of the surfaces of a cellulosic fabric, which method comprises coating the areas of the cellulosic fabric selected for non-dyeing with a polymer emulsion coating composition consisting of about 20 weight percent of a member selected from the grouP consisting of a polyurethane, a polyacrylate and a butadiene-acrylonitrile copolymer, about 1.35 weight percent of carboxylated acrylic polymer, about 1.5 weight percent of ammonium hydroxide, and the balance water, drying the cellulosic fabric that has been coated in selected areas for 15 minutes at a temperature of 60* C. and thereafter dyeing the said fabric with a cotton reactive dye to produce a fabric wherein only the areas not selectively coated by the recited coating composition are dyed. 